﻿// Copyright 2004-2011 Castle Project - http://www.castleproject.org/
// 
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// 
//     http://www.apache.org/licenses/LICENSE-2.0
// 
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#region 导入名称空间

using System;
using System.Reflection;
using System.Reflection.Emit;
using LightWork.DynamicProxy.Generators.Emitters.CodeBuilders;
using LightWork.DynamicProxy.Generators.Emitters.SimpleAST;

#endregion

namespace LightWork.DynamicProxy.Generators.Emitters
{
    public class ConstructorEmitter : IMemberEmitter
    {
        private readonly AbstractTypeEmitter maintype;

        private ConstructorCodeBuilder constructorCodeBuilder;

        protected internal ConstructorEmitter(AbstractTypeEmitter maintype, ConstructorBuilder builder)
        {
            this.maintype = maintype;
            ConstructorBuilder = builder;
        }

        internal ConstructorEmitter(AbstractTypeEmitter maintype, params ArgumentReference[] arguments)
        {
            this.maintype = maintype;

            var args = ArgumentsUtil.InitializeAndConvert(arguments);

            ConstructorBuilder = maintype.TypeBuilder.DefineConstructor(MethodAttributes.Public,
                CallingConventions.Standard, args);
        }

        public virtual ConstructorCodeBuilder CodeBuilder
        {
            get
            {
                if (constructorCodeBuilder == null)
                    constructorCodeBuilder = new ConstructorCodeBuilder(
                        maintype.BaseType, ConstructorBuilder.GetILGenerator());
                return constructorCodeBuilder;
            }
        }

        public ConstructorBuilder ConstructorBuilder { get; }

        private bool ImplementedByRuntime
        {
            get
            {
                var attributes = ConstructorBuilder.GetMethodImplementationFlags();
                return (attributes & MethodImplAttributes.Runtime) != 0;
            }
        }

        public MemberInfo Member => ConstructorBuilder;

        public Type ReturnType => typeof(void);

        public virtual void EnsureValidCodeBlock()
        {
            if (ImplementedByRuntime == false && CodeBuilder.IsEmpty)
            {
                CodeBuilder.InvokeBaseConstructor();
                CodeBuilder.AddStatement(new ReturnStatement());
            }
        }

        public virtual void Generate()
        {
            if (ImplementedByRuntime)
                return;

            CodeBuilder.Generate(this, ConstructorBuilder.GetILGenerator());
        }
    }
}